Muslim Shiites women pray at shrine of Imam Abbas, one of Shiite Islam's most revered figures, during the Shaabaniya ceremony commemorating the birth of Imam al-Mahdi, the 12th holiest figure for Shiite Muslims, in the central Iraqi city of Karbala, on June 24, 2013 the Imam al-Mahdi is the 12th Imam who disappeared in the ninth century and Shiites believe that he will appear before the end of time to establish justice and true Islam in the world.

A Muslim Shiite woman carries a candle near the shrine of Imam Abbas, one of Shiite Islam's most revered figures, during the Shaabaniya ceremony commemorating the birth of Imam al-Mahdi, the 12th holiest figure for Shiite Muslims, in the central Iraqi city of Karbala, on June 25, 2013 the Imam al-Mahdi is the 12th Imam who disappeared in the ninth century and Shiites believe that he will appear before the end of time to establish justice and true Islam in the world.

Muslim Shiite girls carry candles near the shrine of Imam Abbas, one of Shiite Islam's most revered figures, during the Shaabaniya ceremony commemorating the birth of Imam al-Mahdi, the 12th holiest figure for Shiite Muslims, in the central Iraqi city of Karbala, on June 25, 2013 the Imam al-Mahdi is the 12th Imam who disappeared in the ninth century and Shiites believe that he will appear before the end of time to establish justice and true Islam in the world.

Muslim Shiite men burn candles near the shrine of Imam Abbas, one of Shiite Islam's most revered figures, during the Shaabaniya ceremony commemorating the birth of Imam al-Mahdi, the 12th holiest figure for Shiite Muslims, in the central Iraqi city of Karbala, on June 25, 2013 the Imam al-Mahdi is the 12th Imam who disappeared in the ninth century and Shiites believe that he will appear before the end of time to establish justice and true Islam in the world.

Shiite Muslim worshipers gather near the shrine of Imam Abbas, one of Shiite Islam's most revered figures, during the Shaabaniya ceremony commemorating the birth of Imam al-Mahdi, the 12th holiest figure for Shiite Muslims, in the central Iraqi city of Karbala, on June 25, 2013 the Imam al-Mahdi is the 12th Imam who disappeared in the ninth century and Shiites believe that he will appear before the end of time to establish justice and true Islam in the world.

Muslim Shiites pray at the shrine of Imam Abbas, one of Shiite Islam's most revered figures, during the Shaabaniya ceremony commemorating the birth of Imam al-Mahdi, the 12th holiest figure for Shiite Muslims, in the central Iraqi city of Karbala, on June 24, 2013. Mahdi is the 12th Imam who disappeared in the ninth century and Shiites believe that he will appear before the end of time to establish justice and true Islam in the world.

Muslim Shiites pray at the shrine of Imam Abbas, one of Shiite Islam's most revered figures, during the Shaabaniya ceremony commemorating the birth of Imam al-Mahdi, the 12th holiest figure for Shiite Muslims, in the central Iraqi city of Karbala, on June 24, 2013. Mahdi is the 12th Imam who disappeared in the ninth century and Shiites believe that he will appear before the end of time to establish justice and true Islam in the world.

Muslim Shiites gather around the tomb of Imam Abbas, one of Shiite Islam's most revered figures, during the Shaabaniya ceremony commemorating the birth of Imam al-Mahdi, the 12th holiest figure for Shiite Muslims, in the central Iraqi city of Karbala, on June 24, 2013. Mahdi is the 12th Imam who disappeared in the ninth century and Shiites believe that he will appear before the end of time to establish justice and true Islam in the world.

Muslim Shiites gather at shrine of Imam Abbas, one of Shiite Islam's most revered figures, during the Shaabaniya ceremony commemorating the birth of Imam al-Mahdi, the 12th holiest figure for Shiite Muslims, in the central Iraqi city of Karbala, on June 24, 2013 the Imam al-Mahdi is the 12th Imam who disappeared in the ninth century and Shiites believe that he will appear before the end of time to establish justice and true Islam in the world.

Muslim Shiites gather around the tomb of Imam Abbas, one of Shiite Islam's most revered figures, during the Shaabaniya ceremony commemorating the birth of Imam al-Mahdi, the 12th holiest figure for Shiite Muslims, in the central Iraqi city of Karbala, on June 24, 2013. Mahdi is the 12th Imam who disappeared in the ninth century and Shiites believe that he will appear before the end of time to establish justice and true Islam in the world.

Bahraini Shiite Muslim men celebrate the annual festival of Shaabaniya marking the birth of Imam al-Mahdi, revered by Shiites as the coming Messiah, in the village of Sanabis, west of Manama, on June 23, 2013. Mahdi is the 12th Imam who disappeared in the ninth centry and Shiites believe that he will appear before the end of time to establish justice and true Islam in the world.

Shaabaniya Festival

Muslim Shiites gather around the tomb of Imam Abbas, one of Shiite Islam's most revered figures, during the Shaabaniya ceremony commemorating the birth of Imam al-Mahdi, the 12th holiest figure for Shiite Muslims, in the central Iraqi city of Karbala, on June 24, 2013. Mahdi is the 12th Imam who disappeared in the ninth century and Shiites believe that he will appear before the end of time to establish justice and true Islam in the world.